[cxx-interop] Rebase fallout: replace a few instances of swift-5.7 with swift-5.9.

Author: zoecarver

docs/CppInteroperability/GettingStartedWithC++Interop.md

@@ -32,7 +32,7 @@ module CxxTest {
 Add the C++ module to the include path and enable C++ interop:
 - Navigate to your project directory
 - In `Project` navigate to `Build Settings` -> `Swift Compiler`
-- Under `Custom Flags` -> `Other Swift Flags` add `-cxx-compatibility-mode=swift-5.7`
+- Under `Custom Flags` -> `Other Swift Flags` add `-cxx-compatibility-mode=swift-5.9`
 - Under `Search Paths` -> `Import Paths` add your search path to the C++ module (i.e, `./ProjectName/CxxTest`). 
 
 - This should now allow your to import your C++ Module into any `.swift` file.
@@ -81,7 +81,7 @@ After creating your Swift package project, follow the steps [Creating a Module t
 - Swift code will be in `Sources/CxxInterop` called `main.swift`
 - C++ source code follows the example shown in [Creating a Module to contain your C++ source code](#creating-a-module-to-contain-your-c-source-code)
 - Under targets, add the name of your C++ module and the directory containing the Swift code as a target.
-- In the target defining your Swift target, add a`dependencies` to the C++ Module, the `path`, `source`, and `swiftSettings` with `unsafeFlags` with the source to the C++ Module, and enable `-cxx-interoperability-mode=swift-5.7`
+- In the target defining your Swift target, add a`dependencies` to the C++ Module, the `path`, `source`, and `swiftSettings` with `unsafeFlags` with the source to the C++ Module, and enable `-cxx-interoperability-mode=swift-5.9`
 
 ```
 //In Package Manifest
@@ -111,7 +111,7 @@ let package = Package(
             sources: [ "main.swift" ],
             swiftSettings: [.unsafeFlags([
                 "-I", "Sources/CxxTest",
-                "-cxx-interoperability-mode=swift-5.7",
+                "-cxx-interoperability-mode=swift-5.9",
             ])]
         ),
     ]
@@ -144,7 +144,7 @@ After creating your project follow the steps [Creating a Module to contain your
 - Create a `CMakeLists.txt` file and configure for your project
 - In`add_library` invoke `cxx-support` with the path to the C++ implementation file
 - Add the `target_include_directories` with `cxx-support` and path to the C++ Module `${CMAKE_SOURCE_DIR}/Sources/CxxTest`
-- Add the `add_executable` to the specific files/directory you would like to generate source, with`SHELL:-cxx-interoperability-mode=swift-5.7`.
+- Add the `add_executable` to the specific files/directory you would like to generate source, with`SHELL:-cxx-interoperability-mode=swift-5.9`.
 - In the example below we will be following the file structure used in [Creating a Swift Package](#Creating-a-Swift-Package)
 
 ```
@@ -167,7 +167,7 @@ target_include_directories(cxx-support PUBLIC
 
 add_executable(CxxInterop ./Sources/CxxInterop/main.swift)
 target_compile_options(CxxInterop PRIVATE
-  "SHELL:-cxx-interoperability-mode=swift-5.7"
+  "SHELL:-cxx-interoperability-mode=swift-5.9"
 target_link_libraries(CxxInterop PRIVATE cxx-support)
 
 ```

test/lit.cfg

@@ -727,8 +727,8 @@ elif swift_test_mode == 'with_cxx_interop':
     config.available_features.add("nonexecutable_test")
     config.available_features.add("executable_test")
     config.available_features.add("with_cxx_interop")
-    config.swift_frontend_test_options += ' -cxx-interoperability-mode=swift-5.7'
-    config.swift_driver_test_options += ' -cxx-interoperability-mode=swift-5.7'
+    config.swift_frontend_test_options += ' -cxx-interoperability-mode=swift-5.9'
+    config.swift_driver_test_options += ' -cxx-interoperability-mode=swift-5.9'
 else:
     lit_config.fatal("Unknown test mode %r" % swift_test_mode)
 
@@ -2381,7 +2381,7 @@ config.substitutions.insert(0, ('%check-cxx-header-in-clang',
 config.substitutions.append(('%env-', config.target_env_prefix))
 
 config.substitutions.append(('%target-clangxx', '%s -std=c++11' % config.target_clang))
-config.substitutions.append(('%target-swiftxx-frontend', '%s -cxx-interoperability-mode=swift-5.7' % config.target_swift_frontend))
+config.substitutions.append(('%target-swiftxx-frontend', '%s -cxx-interoperability-mode=swift-5.9' % config.target_swift_frontend))
 
 config.substitutions.append(('%target-runtime', config.target_runtime))